Air conditioning system



Mmh 19, 1940.

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IR CONDITIONING SYSTBI Fld April 1B. 1936 9 Sheets-Sheet 4 ATTORNEYS.

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AIR CONDITIONING SYSTEI Filed Aprl 18, 1936 9 Sheets-Sheet 7 CO/V TEOLPAA/EL CIRCUITS' HOLD-OYE@ TANK C'OL/NG ca @j INV ENT ORS @'28 Frh/f L.Mum/1 "5y ATTORNEYS F. L. MURPHY EI'AL AIR CONDITIONING SYSTEM March 19,1940.

Filld April 18, 19356A 9 Sheets-Sheet 8 HEM T C'O/L CGA/WOL PE4/VEL OIl. THEM.

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co/'vneoL WEL c/,ecu/rs- CA@ HEAr/NG Feo/w FLOOR HEAT co/s {gf-mu NR-mwww" mM-m I WIR/N6 CODE Patented Mar. 19, 1940 UNITED STATES PATENTOFFICE z .iassss Am conm'nomo srsm oi' Delaware Application April 1a,193s, ser-mno. 75,242

I Claims.

This invention` relates broadly to air conditioning systems forenclosures, but. for the purpose of disclosure, it will be explainedwith particular reference to its application to passenger 5 car airconditioning.

While there is some similarity between the electrical systems on mostrailway cars in service today, there are nevertheless many variances,due to the fact that not all cars were Abuilt by the i0 same carbuilder, or at the same time and due further to the fact that thecircuits employed are necessarily dependent upon the type of car towhich the system is applied, (i. e. sleeping car. observation car,dining car, business car, coach, etc). Consequently, whenever an airconditioning system is to be appliedl to any particular car, theelectrical control system for the air conditioning equipment must beindividually adapted to the electrical system already on the car, andthis is obviously a costly and time-consuming task.

Among the primary objects of this invention, therefore, are thefollowing: To separate nthe electrical control for the floor heatingsystem a1- ready on most cars from the electrical control of the forcedair heating and cooling system to be applied to the car; to make asimilar separation between the control of the latter system and thecontrol of auxiliary holdover refrigeration equip- :iu ment so that theapplication of the holdover refrigeration equipment may conveniently bemade; to so correlate the parts of the circuit that balanced fusing isfeasible and maintenance, inspection and repair facilitated; to providecircuit means for positively preventing interference between heating andcooling; to provide convenient means for making the main light switchthe master control switch regardless of the particular electricalcontrol arrangement on the car; to proholdover system; and to provideelectrical means for indicating when the cooling system is not videsuitable electrical control for the auxiliary Fig. 3 is a front view ofthe master control panel, :door heat control panel, auxiliary holdovercontrol panel, and indicator lamp compartment;

Fig. 3a is a longitudinal sectional view through the control locker; A 6

Fig. 4 is a schematic wiring .diagram of the entire electrical systemfor controlling the air conditioning equipment, the components of thesystem being shown in their electricalrelation rather lthan their.physical relation;

Fig. 5 is a wiring diagram showing particularly the elements which aregrouped on the control panels and their connectionswith the othercomponents of the air conditioning system. y

Fig. 6 is the same as Fig. 5 except that only the 15 circuits dealingwith car cooling from the overhead evaporator are shown;

Fig. 'l is the same as Fig. 5 except that only the circuits dealing withcar cooling from either the overhead evaporator or the auxiliaryoverhead '20 cooling coil are shown.

Fig. 8 is the same as Fig. 5 except that only the circuits dealing withholdover tank cooling are shown;

Fig. 9 is the' same as Fig. 5 except that only 25 the circuits dealingwith car heating from the overhead heating coils are shown;

Fig. l0 is the same as Fig. 5 except that only the circuits dealing withcar heating from the iioor heat coils are shown.

The specic disclosure which follows of a preferred embodiment of thisinvention is made for the purpose of complying with Sec. 4888 of theRevised Statutes, and is not to be construed as imposing limitationsupon the appended claims except as may be required by the prior art.

General organization The air conditioning system is adapted to be '40used on various classes of vehicles, and the choice of a railwaypassenger car for illustrating an embodiment of the invention is for themost part arbitrary. There are however, some problems in airconditioning railway passenger cars which 45 make the system of thisinvention particularly suitable for application to this class ofvehicles.

The system disclosed includes means for illtering, cooling, anddehumidifying the air in the summer time, and means 'for filtering,heating and humidifying the air in the winter time.

The cooling of the air is accomplished by a reirigerating system whichis operated through a Vvariable speed device from one of the lcar bymotor when the' car is atA stations. The refrigerating system includesparallel evaporator circuits, one of which is adapted to cool the airthat is being delivered to the car interior by direct expansion coils,and the other being adapted .to store up refrigeration in the iorm ofice whenever car cooling is not required and there is .power availablefor operating the refrigerating system.

Car heating is accomplished vicy a steam coil in the path of the airthat is being delivered into the car interior. The steam coil may have ahumidifier associated with it for vdelivering moisture to the air afterit has passed through the coil.

Il. complete disclosure of the physical components of the system as wellas a general disclo sure of theelectrical system controlling theoperation of the equipment may be found in the application of Frank L.Murphy, Phiiip S. Westcott, and Martin P. Winther, Ser. No. 38,562,.filed August 30, i935, and the subject matter of the presentdisclosure.

Briefly, the system includes a refrigerant compressor 200 (Fig. 1)driven while the car is in motion from an axle driven shaft 201 througha magnetic coupling 202 which may be of the type disclosed in the patentto Anthony Winther No. 1,982,461, issued Nov. 2.7, 1934, and when thecaris at stations, by an alternating current standby motor 203. Thecompressor feeds to a condenser 204 cooled by a fan 205 which is drivenfrom the armature shaft of the motor 203 (the -shaft being rotatedwhenever the compressor is operating). An evaporator coil 210 in a.brine tank 20B is connected in parallel with a. direct expansion coil201 mounted in an air conditioning chamber 208 just below the roof ofthe car, and suitable valves, indicated generally in Fig. 1 control theflow of refrigerant to the two parallel-connected coils.

A brine coil 209 is mounted in the air conditioning chamber .208alongside the direct expansion coil 201 and when under certainconditions refrigerant is not available for the coil 201, brine is drawnfrom the tank 200 (where it has been cooled and partly frozen by theevaporator coil in the tank) for abstracting heat from the air beingdelivered into the passenger space.

'I'he liquid line to the evaporator coil 2I0'in the brine tank and tothe direct expansion coil 201 is indicated at 211 and thesuction linefrom these coils at 212. The feed line tothe brine coil 209 is shown at213 and the return line-at Air is drawn from the interior of the carandbeing mixed with the recirculated air) and then forced by blowers 216through the coils 201 and 200 into air ducts 211 located along the sideoverhead heating coil 218 are indicated at 210.

Other physical components of the air conditioning system will beidentified and located as the disclosure of the electrical systemcontrolling the apparatus proceeds.

. Pump relay. l Pump line fuses.

axles when the car is in motion, or by a stand-- Electrical system-ngeneral For convenience of disclosure, the system will bedescribedgenerally from the standpoint of op eration, considering nrst vtheseparable parts of the system, as shown in Figs. 6-10 inclusive, andthen the system as a whole, as shown in Figs. 4 and 5.

The more important components of the air. conditioning system aredesignated on the drawings by appropriate titles in order to facilitatethe disclosure and to avoid confusion, and reference characters will notordinarily be applied to these parts. Also, it will be convenient tolocate certain elements of the electrical system by the use ofcoordinates, particularly in Fig. 4 where thecomponents of the systemare shown in. their electrical relation rather than their physicalrelation.

'111e electrical controls common to all types of cars are as far aspossible placed on a master control panel, generally designated 220, andother auxiliary controls are grouped on a floor heat control panel 221and an auxiliary holdover control panel 222. A master control panel isal- 'ways used but the two auxiliary panels may or may not be used,according to particular requirements.

The' following control equipment is mounted on the master control panel220:

Temperature .selector switch ,ICAir conditioning control).

.Overhead heat relay.

' speed conn-o1 neld discharge resistor.

Line 1118588.

AThe following control equipment is mounted on the oorheat control panel221:

'#1 door neat relay. "#1 floor heat temperature switch.

#2 floor heat relay. #2 door heat temperature switch. #2 floor-heatvalve test switch.

The following control equipment is mounted on the auxiliary holdovercontrol panel 222:

'Cooling selector relay. Holdover switch.

I Referring to Fig. 4, the four basic'control lcircuit groups are (fromtop to bottom) l. Heat controls:l ,l

a. Thermostats and heat relays with interlock control (No. 2 floor heatthermostat circuit is shown in dotted line diagram). b. Heat relay valvecircuit contacts withyalve test switches, heat valve solenoids andsolenoid selection switches, valve line circuit breaker and interlockcontrol (No. 2 door I 2. Blower fan controls. (All those directlyrelated to circulation of conditioned air thru car-an indication ofin-service operation):

a. Blower -fan motor start and speed switch.

b. Cooling thermostat with temperature selection switch and coolingpilot relay.

c. Heat selector relay to place cooling and Aheating selective controlsunder the control of the car attendant for road service (blower fanrunning).

3. Miscellaneous cooling controls:

Circuits used only for holdover system shown in dash line diagram.

Without holdover system (without panel 222) terminals B and C (panel220) are jumpered as shown in dash double-dot diagram.

a. Cooling selector relay (subject to car temperature controls 2-babove).

b. Compressor drive control.

Train in motion-shock relief relay (for speed control).

Train standing- A. C. standby motor starter switch.

Ic. Miscellaneous holdover system controls. Holdover cut-out switch,solution temperature controls, Freon overhead evaporator Valve andholdover coil valve solenoids, compressor rotation switch, and pumprelay. 4. Speed control field excitation and discharge `circuit:

Each of the above basic circuit groups is separately fused, thephysicallocations indicated on Fig. 5. The following diagram shows panel220 cover plate designations, and also the number of the basic circuitas outlined above.

+B i (nl I Bl lie! Iii *Cl IEE! ll IL! Il! (4) (3) (2) (2) (3) (4)Blower fan start switch 235.

Air conditioning temperature selector switch Overhead heat valve testswitch 231 Floor heat No. 1 valve test switch 236 Fuses 239 Cooling testbinding posts 240; and

Speed control test binding posts 24| Projecting through the panel 22|are the following:

Body No. 1 oor heat temperature selector switch 242 Lounge No. 2 iloorheat temperature selector switch 243; and

No. 2 floor heat test switch 244 Projecting through the panel 222 arethe following:

Holdover switch 245; and fuses 246.

The indicator lights, generally designated 241 are mounted in box-likecompartments at the Car cooling from. overhead evaporator 207 alone'I'he portion of the circuit relating to this function of the system isshown in Fig. 6.

Upon closing the main light switch A6,v the circuit to the exhaust fansis energized, as indicated at B6. The blower fan switch C6 is thenturned on, starting the blower fan motor, the field F6 of which is inseries with motor speed resistor taps E6. The blower fan switch alsocompletes circuit to the temperature pilot light H6 (orange) which hasin series with it a resistor a6, the purpose of which is to limit thecurrent to the lamp through the mercury tube d6, which has a resistor h6across its terminals 'to prevent arcing in the mercury tube.

The temperature selector switch G6 is then turned to the right toenergize' the circuit controlling the cooling apparatus including thecooling pilot relay K6. The contacts I6 0f the temperature selectorswitch G6 determine which one of the two mercury tubes J6 controls theoperation of the cooling pilot relay K6 which in turn governs the entirecooling system.

Assuming the temperature selector switch is in the high position, asshown in Fig. 6 and that the high cooling thermostat J6 calls forcooling, the cooling pilot relay K6 is energized which closes thecontacts of the shock relief relay L6, thereby energizing the speedcontrol field M6 to drive the compressor from the car axle. The speedcontrol windings M6 are in series with a caterpillar resistor N6 Whichchanges the resistance in the field circuit in a manner fully describedin the Winther patent heretofore identified, thus limiting the speed 0fthe compresso to some predetermined maximum.

When the cooling pilot relay K6 has been energized, and the shock reliefrelay has closed .the circuit through the speed control circuit M6, anopal light O6 is illuminated to indicate that the speed control circuitshave been properly closed.

A high pressure, low pressure switch P6 is located in the refrigerantline to cut out the compressor in case of pressures which exceed or fallbelowv predetermined maximum or minimum values. The switch P6 isconnected in series with the operating coil of the shock relief relay L6so that whenever head pressures or suction pressures become dangerous,the refrigerant system is shut down.

At stations where the refrigerating apparatus is to be operated bystandby power,l as for example 220 volt, 3 phase current, a plug Q6 isfitted into a power receptacle to operate an A. C. motor for driving thecompressor, but the circuit through the alternating current standbymotor is not closed until the plug has been pushed into the receptacle asufficient distance not only to connect the three A. C. lines with thecorresponding wer lines but also to close the circuit through two D. C.terminals which energize the coils R6 of an A. C. starting switch andclose the contacts T6 to energize the A. C. standby motor. At the sametime, the upward movement of the armature opens contacts S6 (before thecontacts T6 are closed) which prevents the speed control field M6 frombeing energized at the same time that the A. C. standby motor isrunning.

. The heat selector relay U6 operates during u car cooling selection toprevent heating from interfering with cooling. This is accomplished bymeans of the rotary interlocking switch V8 which moves under commoncontrol with the cooling temperature switch I6.

The terminals CH and CT project through the cover plate of the panel 229(see Figs. 3 and 6) so that they may be easily shorted for test- .'ingthe operation of the system even though the cooling thermostat J6 doesnot callfor car cooling.

Terminals SCT and SC likewise project through the cover plate in orderthat the caterpillar resistance N6 of the speed control may be readilytested.

Car cooling from either overhead evaporator 207 or auxiliary overheadcooling coil 209 This portion of the electrical controls is shown. inFig. 7.

The functioning of the circuit up to and including the energization ofthe cooling pilot relay K1 is the same as described under Car coolingfrom overhead evaporator 207. (A1 of Fig. 7 corresponding to A6 of Fig.6; B1 of Fig. 'l corresponding to B6 of Fig. 6, etc.)

The closing of the cooling pilot relay K1 energizes the cooling selectorrelay KK1 which in turn (a) Closes contacts 2 for holdover cooling,subject to availability of the compressor through action ofA therotation switch W1.

(b) Closes contacts 3 for energizing the evaporator solenoid X1, subjectto availability of the compressor through action of the rotation switch'(C) Closes contacts 5 for energizing the shock relief relay L1.

The energization of the shock relief relay L1 closes the contacts whichcontrol the energize.-

tion of the speed control eld M1, thereby drivi When the tspeed of thecar falls below a pre determined minimum, the contacts 8 of thecompressor rotation switch W1 are opened and the contacts 1 are closed,the latter contacts being in series with the brine pump relay Y1 andalso in series with the contacts 2 of the cooling selector relay KK1.lTherefore. when the car is travelling below a predetermined minimumspeed, or is at stations where alternating current power is notavailable and the cooling pilot relay K1 is energized, the pump relay K1closes contacts which energize the circulating pump -Z1 and causes brineto be 0circulated through the auxiliary overhead cooling coil 208..

, Holdover tank cooling The circuits dealing with holdover tank coolingare best shown in Fig. 8 (some reference. however, being made to Fig. 1for related clr, cuits).

Before refrigerant is permitted to flow through the evaporator coil inthe brine tank 288, all demand for car cooling must be satisfied. Whenatascos temperature selector switch, the closing of the circuits forfreezing the brine is made dependent upon the cooling pilot relay K1(Fig. 7) In other words. when the contacts of the cooling pilot relayare open, either because the cooling thermostat J1 does not call forcooling or because the temperature selector switch is set to oTposition, the circuits for refrigeration control of the holdover tankare unlocked and the flow of reirigerant through the evaporator coil inthe brine tank is permitted subject to suitable control.

Assuming, then, that the circuit through the cooling pilot relay K1(Fig. 7) is open, which in turn causes the cooling selector B8 (Fig. 8)to become de-energized, and assuming also that the auxiliary holdoverswitch A8 is closed, as well as the main switch light, the armature ofthe cooling selector relay B8 (a) Closes contacts I to the solenoidvalve H8 which controls the flow of liquid refrigerant to the holdovercooling coll 210; v

(b) Closes the contacts 4 to the compressor power circuits through themaster control panel 228.

The flow of refrigerant through the holdover cooling coil in the brinetank 288 is controlled by a low pressure switch C8 and a temperatureswitch D8, the two being connected in parallel. 'I'he former isconnected in the, suction line from the holdover cooling coil 2I|l andmeasures in effect .the average internal temperature of the ice blockduring formation, openinga pair of contacts when the pressure dropsbelow a predetermined value. 'Ihe latter consists of a thermostatic bulbpositioned a given distance from the evaporator coil and as soon as thebulb is encased with ice from the growth on the evaporator coil, it actsto open a pair of contacts and thereby .perform its part in controllingthe flow of refrigerant to the evaporator coll.

The reason for using a combination of pressure and temperature controlin the brine tank is fully disclosed in the Murphy, Westcott and Wintherapplication herenbefore identified, and further discussion here isdeemed unnecessary.

It should be noted that either the pressure switch C8 or the temperatureswitch D8 is capa.- ble of closing the circuit for operating thecompressor, but that both switches must be opened to break thecompressor' control circuit. This is due to the fact that thetemperature and pressure switches Cl and D8 are connected in parallel.

lIn road service, when the holdover tank calls for ice formation througheither the pressure switch C8 or the temperature switch D8 (and assumingthat car cooling is not called for), the shock relief relay E8 isenergized, which in turn energizes the field coils F8 of the speedcontrol, causing the compressor to be placed in driving connection withthe car axle. Then, if the compressor rotation switch G8 is in theposition shown in Fig. 8 (due to suiilcient car speed) the valve andpermits refrigerant to ilow through the coil 2li.

At stations where standby A. C. 220 volt power is available, the plug 18 is pushed into the power receptacle and the compressor is operatedfrom the A. C. standby motor in the saine7 manner as has been previouslydescribed. It will be understood that when the armature of the A. C.starting switch J8 is lifted, the circuit through the speed controlfield F8 is opened at KI through the shock relief relay EB, before thearmature reaches the end of its stroke to close the circuit through theA. C. standby motor at the contacts L8.

It will be noted that the check valve in the suction line of theholdover evaporator not only serves to prevent refrigerant fromcondensing in that coil, but also makes possible the combinationpressure and temperature control for the holdover coil. I f a checkvalve were not used, the pressure within the holdover coil would quicklyrise to a point sumcient to operate the pressure switch, and as a resultholdover cooling would be effected even though not desired.

Car heating from overhead heat coils The description which follows hasparticular reference to Fig. 9.

On closing the main light switch AI, the exhaust fan circuits indicatedgenerally at B9 are energized. The blower fan switch C9 is then turnedon which energizes the blower fan motor field F9 through one or moreresistor taps El depending upon the position to which the switch isthrown. The switching on of the blower fan also energizes the selectorrelay I9 thereby (a) Closing contacts l which connect negative batteryto one side of the overhead heat relay M9 and (b) Closing contacts 2'which connect positivo battery to the 'inside contacts Ji of thetemperature selector switch.

The temperature selector switch is then turned to the left which (alSelects one of the temperature control tubes L9 as the means forgoverning the action ci' the overhead heat relay (the contact Kl of thetemperature selector switch in this instance being the one ior mediumheating).

When Ithe mercury in the medium thermostat tube L9 closes its contact,the overhead heat relay M9 which is normally energized is shorted across3' and 4'.

Assuming that the car calls for heating and that the overhead heat relaycontacts are, therefore, in the position shown in Fig. 9, the solenoidt' is energized and draws the plunger I to the right, thereby rotatingthe valve handle 'I' and the valve stem'to open the steam port to admitsteam to the heat coil 2I8.

Before the plunger reaches the end ot its travel, the valve handle l1trips a toggle'switch l' which opens the circuit to the solenoid i" andprepares the solenoid 9' (adapted to move the plunger-8 in the oppositedirection)l for turning of! the steam when no further heating isrcquired.

When the temperature in the car rises sumciently to close the contact atL9, the operating coil of the overhead heat relay Mi is aborted across 3and 4' to move the amature against contacts which close theclrcuitthrough the o3 solenoid of the overhead heat valve Nl therebyshutting oir the steam to the heating coil.

In a similar manner, when the plunger 6 approaches the end of itstravel' to the left, the toggle switch 8' is tripped to' open thecircuit through the off solenoid 9' and prepare the on solenoid l' foraction when heating is again to sticky valve operation by introducing athermal element O9 in the circuit. Whenever either one of the coils or 9is energized for more than a predetermined period of time, the

thermal element O9 closes the contacts lto energize the circuit breakerrelay P9 and thus open the valve operating circuit through the contactsIl'.

When the temperature selector switch is rotated to the right (coolingside) the inside contacts J9 are separated, thereby disconnecting thepositive battery line from the overhead heat relay M9 to disconnectthermostat control and insure that the valve circuit contactor ofoverhead heat relay M9 is in the ofi position.

At the same time, the two other inside coritacts are connected (when thetemperature selector switch is rotated to the right) to provide apositive battery supply to the overhead heat valve line even though thetest switch 5 may have been left in manual position. As a result, energyis only supplied to the o solenoid 9' of the heat valve N9 in order toprevent heating from interfering with cooling.

Car heating from'jioor heat coils The. description which follows hasparticular reference to Fig. 10.

It is desirable to provide some means for insuring that sumcient heatwill be supplied to the car under any and all circumstances to keep thepipes from freezing. For example, when the car is left in the yard andthe car attendant has opened the main light switch All), as iscustomary, an auxiliary thermcstatlcally controlled heating systemfurnishes sunicient heat to the iioor heat coils to keep the car fromfreezing.

llt is also desirable to .be able to use the iioor heat coils asauxiliary heating means during cold weather when the overhead heat coilis operating to take the main heat load.

When the car isl left in the yards and the attendant has opened the mainlight switch All), the exhaust ian circuits indicated diagrammaticallyat Bit are also open as well as most of the air. conditioning controlcircuits (see Fig. 4). As a result, the blower ian start switch CID maybe either open or closed since the light switch All) is the primarycontrol, and the heat selector relay DIU is necessarily de-energized.The temperature selector switch EIO may be left in any position as theinside switch contacts (the heating and cooling interlock) 4 and 5 ofthe heating and cooling interlock switch are shorted at l" on theselectorrelay Dill to supply positive 'battery current to the floor heatrelays JIII and Kill, and the contacts 6" and 1" of the heating andcooling interlock switch are shorted at 3" on the selector relay DIU tosupply positive while A. C. standby poweris available.

d. Speed control eld (D--Ih being deenergized leaves the driven unit(neld rotor) free of magnetic coupling to the car axle drive.

e. Standby motor starter switch closes, completing A. C. circuit todrive motor, which is shaft-connected to speed control driven unit, andto compressor which is belted to it. l

. Compressor rotation switch (I3-I3) transfers, completing circuit toevapo' rator solenoid valve (FL-I3) which opens and admits Iireon toevaporator circuit.

B. Holdover or secondary car cooling.

No compressor driving power available.

a. As compressor does not rotate, compressor rotation Vswitch contactsv(K-i) remain on holdover pump relay circuit.

b. i-IoldoverV pump relay energized e. Holdover pump relay contactsclose (E-ii).

d. l-loldover pump motor (C-H) runs to drive cold holdover solution fromthe storage tank to the auxiliary overhead cooling coil and return tothe spray header of the storage tank.

Temperature pilot light (F--i-l).

Ine temperature pilot lamp lights when car is too Warm (80 is reached),when special damper for fresh and recirculated air control,

should be shifted to increase recirculated air and decrease fresh airuntil lamp goes out again. The pilot light is controlled directly froma.

heavy duty thermostat tube (E-S) mounted on the same plate as thecooling thermostat tubes.

Electrical operation is as follows:

Below 80, the thermostat tube by-pass resistor (E-Q) is in series with apermanent line resistor (CP-9), the two together. limiting voltageacross the lamp to about 5 volts on a 32-volt supply line (filamentburns at a dull red color).

At 80, mercury column (Ef-9) closes shunt circuit around the by-passresistor (El- 0),

raising lamp voltage to about 25 volts.

The line resistor (C1- 9) (always in circuit) limits the maximum currentthe thermostat tube (E-9) must carry.

The by-pass resistor (Ei- 9) prevents a complete open circuit conditionwhen mercury column drops and opens shunting circuit, and so reducesarcing at surface of mercury column (E-9) to an amount not harmful.

Holdover tank cooling (in service).

(Cooling of car must be satisfied before compressor capacity is madeavailable yfor holdover tank ice forming).

Cooling thermostat tube mercury column (F-ill or F-H) lowers untilcircuit is broken to the cooling pilot relay (Gf-l0).

a. Cooling pilot relay (G-IU) is de-energized.

Coolingpilot contact (I--l I) opens.

b. Cooling selector relay (Q -l2) de-energzed.

Cooling selector contacts (G-II and G-ED disconnect car cooling, controlcircuits and return to back contact position to allow holdover tankcooling as may be required. Y

l Holdover toggle switch closed (1 -I2).

Holdover pressure and temperature switches closed. (H--i2, H-IB.)

Compressor driven from either speed control (DA-I4) (train operation),or standby motor (external A; C. power available) through' the operationoithe same control circuits described previously under carcooling-Primary evaporator.

Operation of holdover tank low pressure and temperature switches isbrieiiy as i'ollows:

a. Low pressure switch (H-i!) operation controlled by lioldover tank4ireon coil suction line pressure (o. measure of average internaltemperature or ice block during formation). Closes at 23 lbs. and `openscircuit at i0 lbs. b. Temperature switch (Q -i2) conI trolied by bulb intemperature well so placed that the warmed holdover solution from thespray header during secondary or holdover cooling of car will exposesame to the warmer solwtion as soon as the surface begins to melt. Thisallows rereeaing of surrace ice without having to melt down the bulk cithe calce, which would be f. necessary to cause the low pressure switchto close again citer an initial freezing. Closes circuit at 38 degreesand opens circuit at 34 degrees.

Nora-Either switch completes circuit, but both must be open to breakcircuit.

Pre-cooling of holdover tank in Yard, without being subject to thecondition ci car cooling operation first, may be accomplishecl by:

c. Closing main light switch (ii-2) b. Leaving blower fan switch oi (00,

c. Closing holdover toggle switch (I-i2) c3.. Plugging in A. C. standbypower for running standby motor. (D. C. intei-lock contacts at B-i2.)

' Car heating Close main iight switch (rl-2).

Exhaust fans run. (F-i) Close slower ian switch (C-s, H-i

Selector relay energized. (YL-s).

c. @pens yard (Out-of-service) interlock contacts ((3-3) to heat valvetest switches (D-2, 'iD-Ei, iiD-4l) and heat relays (F-, F- and lit-S)in order to transfer control to the inside interlock switch (0 2 andC-l) of the temperature selector switch assembly (F-- and lil-i0). A

b. Completes circuit (D-S and H-) to overhead heat ther'- mostat (Gf-7Jand G-) and reIay'T-).

Temperature selector switch (lL-3) (.Air conditioning ccntrol) -rotatedto the left to select desired overhead heating temperature.

Inside or heat interlock switch (C-1) (rotated under common control withthe Aswitch for thermostat tube temperature selection) operates to:

` l @,Qu

c. @pen @-3) heat valve tery circuit for another current imtest switches(l1-2, pulse to free the valve. B-li when thrown to man- When valvecontinues to stock, the above ual position (see outline on cycle ofcircuit breaker operations re- Circuit hrealrer operation). peat-saccordingly. 5 A t. Completes (B) circuit L-ll) ,to When attendantnotices heat valve pilot all heat relays and A lamp G2) is lighted, thefollowing per- F-Q). talus: Overhead heat: c. Valve test switches (i3-2,D-S or n@ Overhead heat thermostat tube mercury D-) normally set atautomatic" column (Q3-l and @-8) too low to position, are each in turntransloridge overhead heat relay' wlneling ierred to manual position.(F-Sl), thus energizing it (car heating b. The test switch which causesheat called for). D pilot light to go out, indicates on g55 Overheadheat relay contacts (l- Q) corresponding name plate, which 15transferred to on position. circuit is involved. Overhead heat valve onsolenoid c. Valve test switch of the circuit indi (F-l) energized.eating valve trouble, le lett in 'Valve solenoid plunger shifts,rotating manual position, disconnecting a@ valve arm to open steam portand admit valve from automatic thermostat steam to heat system. control.

At end of valve arm swing, solenoid toggle d. Attendant `manually shiftsvalve arm switch (Cm-l) disconnects on solenoid back and forth, to freesame and; connects on solenoid. (EF-5), in. possible. 2li preparationfor oh valve operating cur- Y Ii able to secure free' action once 25rent from heat relay contact (Ei-Q) when more, the test switch isreturned to car is sumciently warmed (mercury cols ,"automatic position.umn) (G-l?, 'EE-8) in thermostat tube l not able to clear the trouble,valve rises to bridge across heat relay winding is 1eft free ofelectrical control. s@ (IF-9)). v (Test'switch left in manual posia@ lFloor heat Y f. tion) and valve operatecl by hand Temperature selectorswitch rotated to until terminal is reached for reone of the overhead'neat temperature pairs. D TF' 0. msgectilxtpog Qsj Q m: Yord, storage(out-o-sercice condition) s F-E) (two on panel 22B) turned., to Mainlight switch {Pr-2) open. select floor heat temperature desir-eci.Exhaust fans (F-i) not running.

Floor heat relay (F-S or F--ll (two on Blower fan switch open (0 9,H--9).

panel 22!) energized when Hoor heat Selector relay de-energized (F-).

40 `thermostat; mercury column (Gl-5 or a. Disconnects both power (D-I)40 G-G) is too low to bridge relay and H-8) to overhead heat relaywinding (El-6 or F--ll- (heating y (IF-8). called for) b. Floor heatrelay (El-S or F-ll) (two on Valve control is similar to that describedpanel 22 i) but under the control of floor for Overhead heat operation.heat temperature switch (F--S or F-l) vllt? Circuit breaker operationwhich assures full thermostatic control A sluggish or sticking valveoverheats to prevent car freezing up in winter, circuit breaker thermalelement when car is out of service. (B+) power (H-l) (in series with allheat valve to iloor'heat thermostat circuits supplied 4w (F-Z, F-, F-l)solenoid N lines) through heat selector relay (EL-9) yard 56 Thermalelement warps control contact operation interlock. (C-ll), which is(G-E) closed. closed in this case.

a. Magnetic hold-ln winding ci thermal c. Completes supply (0 3) tovalve test unit assembly, energized (Gb-l) switch manual position (iD-2,D-iB, b. Circuit breaker relay winding ener- D-l) terminals. 55

gized (Ch-l) Heat valves must have operating current c. Relay contacts(Ci-2) open. leaving supplied to either onfy or oil solenoid heat valvepilot light (G-2) in seoperating windings as valve does not rerles withvalve solenoid line, reduc return to off position automatically. .60 ingvalve operating current to onli7 Selector relay contact (C-) assurescuro0 enough to light the pilot lamp. 1 rent supply to heat relaytransfer con- Thermal element (EE-l) cools down. tacts (1E-2, E-S, E-)for proper Magnetic hold-in winding (Gi) revalve control, even thoughvalve test tards return of warping member switches (D-Z, D-3, D-I) maybe in- 35 (HV-l) to normal, (open contact pomanual position. 65

sition) until thermal unit (H-I) is thoroughly cooled down and hold-inGeneral operation notes winding (G-l) can no longer oppose Testterminals are provided on the panel 220 for return tonormal. Coolingtest" and (speed control) S. C. Test.

Thermal element contact (H-I) opens. Cooling test consists of snortingaround the 70 a. Relay (G-D deenergized. cooling thermostat (F-III andF-I I) to create b. Relay contacts (Gl-2) close, by-passartiilcial carcooling control, for checking cooling pilot light (G2) and reconingoperation. necting valve solenoid circuit Speed control test is arrangedto check the yconn .uw (E z' E s p ydimtiy to bctdition of thecaterpillar resistance contacts 1s Heating-cooling interlock 'I'heoutstanding feature of the heating-cooling interlock is that thecircuits prevent heating from interfering with cooling, and vice versa,and yet insure that the floor heat system is in operation during yardservice. Specifically-during cooling-z 1. All heat thermostat relaysassured to be in the olf position.

2. All heat relay contacts for operating heat valve solenoid circuitsassured to be in the off" position.

3. Flow of current to the heat valve solenoid windings is asssured (theheat relay contacts being in off position means that the current goes tothe ofi solenoid of the valve). During yard service:

1. Floor heat relay circuits energized to guarantee floor heat controlto prevent freezing or allow preheating of car before service (with apositive flow of current to iloor heat valve solenoids).

2. Overhead heat relay control is off (with a positive supply of currentto oiT' solenoid).

Car heating in road service The system provides full protection andcontrol of floor and overhead heating but at the same time allowsoperation of valve test switches in determining faulty valve operation.

In yard service and during cooling, it is desirable to have the manualside of the test switches connected directly to the power supply so thateven if a yard man accidentally leaves the test switch in manualposition, the heating valves will be turned off (the heat relays beingde-energized by reason of the heating interlock for the relays) whichputs the valve contacts to off position, and, therefore, guarantees asource oi current for operating the heat valve solenoids. During carheating in normal road service, it is desirable to have the manual sideof the test switches disconnected from the battery so that when the heatpilot lights, the faulty valve may be locatedby opening successively thevarious valve control circuits by means of the test switches until thecircuit which caused the light to stay on is broken, whereupon the lightis extinguished.

Interlock between blower fan and the cooling and heating selection Themainpurpose of this interlock is to prevent the heating and coolingcircuits from be'- ing operative unless the blower fan is operating toenable them to do some useful work. In one sense, the blower fan circuitis an indicator that the system is in condition for road service.Another purpose is to ensure that 'the blower fan is operating when theevaporator is in service to prevent the latter from freezing up. v

Specifically, the blower fan start switch energizes the heat selectorrelay and the cooling side of the temperature. selector switch, theheating side oi' which is under control of the heat selector relay.

The function of cooling pilot relay Control of cooling thermostatoperation is directed into a cooling pilot relay located on the masterpanel so asto provide a flexible arrangement whereby the cooling pilotrelay contacts may be used to secondarily control any combination ofcooling circuits required.

For example:

l. Cooling pilot relay may directly excite shock relief relay to operatethe speed control in an axe drive mechanical air conditioning system.

2. Cooling pilot relay may excite cooling selector relay located onseparate hold-over control 4panel which in turn sets up individualcontrol circuits including car cooling through the primarycompressor-evaporator system, car cooling through the brine auxiliarycooling system, and brine tank liquid cooling from the compressor.

3. Pilot relay contact may be used to complete circuit to excite astandby motor A. C. starter switch coil.

4. Cooling pilot relay contact may be utilized to excite the startingrelays of a direct current motor to drive the compressor as in the caseof the electro-mechanical air conditioning system.

5. Cooling pilot relay may be used to operate the ice water pump orby-pass valve relay of the ice system of air conditioning.

Speed control field excitation circuit The shock relief relay is anintermediate relay under the control of the cooling pilot relay forcompleting the circuit to excite the speed control field as required.When disconnecting the speed control eld after a cycle of operation, theinductive discharge across the contacts of the shock relief relay tendsto seriously damage them from arc burn and a by-pass condensor acrossthe shock relief relay contacts is provided to act as a shunt circuit toabsorb the rush of induced alternating current when the shock reliefcontacts are opened. An additional protective fuse is put in series withthe condenser because when a condenser fails, it is generally a case ofinsulation breakdown and unless a fuse is provided to open the circuit,a short circuit condition would result which would short the entirespeed control leld circuit.

The induced voltage set up with the disconnecting of the speed controleld by the shock relief relay contacts at the end of a cooling operationtends to burn out the cooling pilot light intended to operate at normalbattery voltage. To allow use of a standard car lighting type lamp andstill not suffer from high induced voltage, a by-pass resistor isinserted across the cooling pilot light tc provide a discharge path fromthe A. C. current set up through the cooling pilot light circuit.

Shoclc.relief relay interlock with A. C. standby service Y The A. C.standby motor starter switch asv sembly provides a normally closedinterlock which providesl means of completing the circuit to theshockrelief relay unless the A. C. standby motor Compressor rotationswitch The compressor rotation switch is intended as a means ofelectrical circuit selection depending upon availability of thecompressor. When the compressor is running, whether vfrom standby poweror through the speed control in road service, the compressor rotationswitch completes one side of the circuit to the overhead evaporator andthe holdover Freon solenoid valves.

Whenever the compressor is not available, the compressor rotation switchreturns to normal to complete one side of the circuit to the brine pumprelay.

Cooling selector relay The cooling selector relay is mounted on theauxiliary holdover panel and is subject tocar cooling control throughthe cooling pilot relay.

The operation for car cooling involves:-

l. Completion of circuit to the holdover brine pump relay (subject tocompressor rotation switch, i. e. compressor availability).

2. Completion of circuit to evaporator solenoid `valve (subject to,compressor rotation switch,

i. e. compressor availability).

3. Completion of .circuit through high pressure land low pressure i'reonswitch to the cornpresser power control circuits which may result in (a)Normal excitation of the shock relief relay for speed control operation,or (b) Standby A. C. motor operation.

The operation for forming ice in the brine tank involves:

l. Completion of compressor power circuit through high-low pressureFreon switch to 'operate compressor by either (a) Normal shock reliefrelay excitation for speed control operation.

(b) Standby A. C.motor operation.

2. Completion of circuit to holdover Freon coil solenoid valve (subjectto compressor rotation switch, i. e. compressor availability).

Both auxiliary holdover functions of the cooling selector relay aresubject to holdover tank temperature switch and Freon suction side lowpressure switch operation.

The cooling selector relay is made to complete all the interlacedcircuits with one mechanism so that l. Car cooling has prior controlover auxiliary tank cooling, the latter being available only when carcooling, is satised, and

2. When car cooling is called for, compressor availability willdetermine whether the compressor power circuits are energized, or theholdover pump relay.

Temperature (30) pilot light This nent is used t@ visually indicate thata critical temperature has been reached for cooling service (chosen at80) To maintain a common standard of thermostat tube mounted in a commonmounting with cooling thermostat .tubes which are placed so as to becontrolled by the temperature of the recirculated air, special circuitconditions are required to allow operation of a. pilot light by thethermostat tube directly.

'This is because of the fact that the amount of light and thusrestricting the current through' ramasse the thermostat to an amountwhere suiiicient illumination is given by the light to be readily seenby the operator.

Whenever the temperature in the recirculated air duct is 60 or above,the mercury column completes the circuit to the pilot light (causing itto be fully illuminated) indicating to the operator that the car is toowarm and that steps must be taken to correct the condition and cool thecar down to the normal operating range. This Imay be a case ofreadjustment oi the fresh and recirculateol air damper to reduce thefresh air and increase the :re-circulated air, as in normal service, orit may be an indication that there is faulty operation of the coolingsystem otherwise unnoticed but brought to attention by the fact that thecritical temperature of has been reached.

Whenthe air has cooled down below 80 and themercury column is separatedin the thermostat tube, instead of open circuiting the line to the pilotlight vwhich tends 'to create destructive arcing. at the surface oi themercury in the tube, a thermostat lay-pass resistor (Fig. i E23) isprovided which means then that when the thermostat mercury column, isbelow the 80 critical point, the current through the lamp is merelyreduced down to a point where, while the lamp still glows at a dull red,it is insufcient to give a 'false indication. Thus, the thermostat tubemerely acts to change the voltage across the pilotl light betweencontrolled minimum and maximum limits rather than .between a conditionof zero current and the maximum required for full illamination at normalline voltage.

General 'panel arrangement Certain circuits such as the main controlcircuits dominated by fuses marked CC+ and CC are best operated from thecar lighting circuits to take advantage of the controlled line voltageeffected by the lamp regulator, the latter being almost universally usedon railway cars to stabilize the voltage to the car lighting circuitswhen the axle driven generator is operating at high speed.

Certain other circuits, such as the heat control circuits, may besatisfactorily operated from oil! the-battery circuit direct regardlessof voltage uctuations.

The main light switch in the switchboard locker of the car becomes themaster switch for ail electrical equipment in the car with the exicaption of the heat control circuits for floor heating which must remainindependent subject to the cooling operation interlock, in order toprevent freeze-up of the car in the winter when out of service. Thus,the main light switch becomes the key also to the operation of the airconditioning controls so that when the main light switch is opened, theair conditioning is com r pletely shut oi too.' The electrical load puton the` system by the blower fan is sullicient to add an xexcessiveoverload to the lamp regulator. Therefore,'it becomes essential that thecircuit to the blower fan be excited by the main line switch only on theline opposite in polarity to that which involves the lamp regulatorcontrolled resistance group, whereas the opposite side of theblowerid'an circuit is returned direct to thebattery. In this manner,the main light switch remains the.l key switch to the system and at thesame tim'ethe lamp regulator is not overloaded.

As many railroad cars have circuitapplica.- tions where thelamp-regulator is in the positive lamp line necessitating the main lineswitch control to be in the negative lamp line, which is opposite inarrangement to that usually used on Pullman equipment, a means of easymodication of the master panel to provde for these external conditionsfor universal application of the panel to any car is covered in thearrangement of the power line terminals to the board.

The blower fan circuit terminals indicated as +F and -F are keptindependent from other circuits on the board. The +L and -L lamp linepower terminals feed the control circuits CC+ and CC- as well as thespeed control circuits SC+ and SC-. The B+ and B- terminals feed allheat circuits and the auxiliary holdover brine circulating pump motor.By convenient method of inter-terminal strapping +F can be connected toadjacent terminal +L on one side of the power with -F connected to -B onthe other side of the panel by an equivalent interconnecting strap. Thiswould be for Pullman service application. V

If the same panel is to be used for application to railroad owned cars,+F would be connected to the opposite adjacent terminal +B and on theother side of the panel, the strap would be changed to connect -F to -L.

All circuit fusing is so arranged as to systematically segregate eachmajor grouping of panel circuit controls without overlapping so that incase of fuse' trouble, there is no doubt left as to the circuit in whichthe trouble is to be found, thus providing quick and accuratesegregation of circuits. 'I'his also allows balanced fusing on bothsides of the line for a given circuit, the fusing being of minimumcapacity to take care of the particular needs of that circuit, therebyproviding a greater factor of safety in fuse protection than would bepossible where the circuits interlace as has been done in priorinstallations of this character.v Y

Fuses are also located on the board in a systematic manner so that thevarious circuits may easily be checked.

Terminals at the top and bottom of the master panel are so located as tomatch up with equivalent terminals for oor heat and holdover panelsproviding quick and accurate means of expanding the function of themaster panel to suit car conditions whenever any sort of sub-panel isadded.

Summary The particular advantage ofthe control panels which have beendescribed is that they may be used on all types of railway cars withoutmodication. Furthermore, they are adaptable not only to air conditioningsystems in which the compressor is driven through a magnetic clutch fromthev car axle, but also to electro-mechanical systems where thecompressor is driven by an electric motor energized by the axlegenerator, and to ice systems which are interlocked with heatingsystems.

It will be understood that various parts of the control equipmentmounted on the master control panel 220 may be eliminated under certaincircumstances, and other equipment may be substituted in its placewithout departing from the spirit of this invention. Such modificationswould necessarily be made if the control panel were to be used with anelectro-mechanical system for example, but the important thing is thateven this use of the panel does not necessitate making up a new panel orcompletely revising the control equipment. Formerly, every time thesystem was changed in any minor detail, an entire new panel wasnecessary, even though the change in the old panel was in some slightdetail.

Although no means for humidifying the air in the winter time is shown inthe drawings, it will be understood that a water spray may be placed inthe air conditioning chamber and controlled by a hygrostat for supplyingthe proper amount of moisture to the air.

This application is closely related to a co-pending application led bythe same applicants and bearing Ser. No. 62,004, filed February 1, 1936.Reference is made to that application for subject matter disclosed butnot claimed in the present application.

What we claim, therefore, is:

1. In an air conditioning system, a cooling circuit, a heating circuitincluding a iloor` heat valve having on" and orf solenoids, thermostaticmeans for selectively energizing said solenoids, and means forpositively supplying current to the off solenoid whenever the coolingcircuit is in operation.

2. For use in an air conditioning system, a floor heat valve having onand off solenoids, thermostatic means for selectively energizing saidsolenoids, a manual test switch for the floor heat valve, and means forpositively supplying current to the off solenoid even though the manualtest switch is left in test position.

3. For use in an air conditioning system, a cooling circuit, a heatingcircuit including a floor heat valve having on and off solenoids,thermostatic means for selectively energizing said solenoids, atemperature selector switch for determining which circuit shall be inoperation, means associated with the temperature selector switch forpreventing heating from interfering with cooling, said last named meansbeing adapted to positively supply current to the off solenoid wheneverthe cooling circuit is in operation,

4. In an air conditioning system, a main heating circuit including aheat thermostat, a cooling circuit including a cooling thermostat, atemperature selector switch for selecting the circuit to be inoperation, means associated with said switch for preventing bothcircuits from being in operation at the same time, an auxiliary heatingcircuit including a floor heat valve thermostat, and means' forassociating the auxiliary heating circuit with the main heating circuitso that` the former is also subject to the heating and cooling interlockassociated with the temperature selector switch.

5. In an air conditioning system, a heating circuit including a heatthermostat, a main cooling circuit including a cooling thermostat, atemperature selector switch for selecting the circuit to be inoperation, means associated with said switch for preventing bothcircuits from being in operation at the same time, an auxiliary coolingcircuit including controls for an auxiliary holdover refrigeratingsystem, and means for associating the auxiliary cooling circuit with themain cooling circuit so that the former is also subject to the heatingand cooling interlock associated with the temperature selector switch.

6. In an air conditioning system for railway cars-including arefrigerant compressor driven through an electromagnetic speed controldevice from one of the car axles, a speed control circuit forcontrolling the operation of said device, a heating circuit including aheat valve solenoid and a thermostat, an air flow circuit including ablower switch, and means for alter-

